Number Six is a family of fictional characters from the reimagined science fiction television series, Battlestar Galactica. She is portrayed by Canadian actress and model Tricia Helfer. Of the twelve known Cylon models, she is the sixth of the "Significant Seven". Like the others of the "Significant Seven", there are several versions of her, including Caprica-Six, Shelly Godfrey, Gina Inviere, Natalie Faust, Lida and Sonja. She is the only model that does not use one particular human alias for all copies.